After the philosophical (rational), the traditional (transmitted), the historical and the miraculous evidences, there is also the evidence of consensus (Ijma) pointed to by some of those who believe in the theory of the existence of Muhammad bin Hassan Askari and his birth.

The first person to point to this evidence of consensus was Sa’ad bin Abdullah Ash’ari al-Qummi in ‘Al-Maqalat wa al-Firaq’, p. 106.

 Sheikh Saduq has reported from Nubakhti that: the entire Shiites have agreed (have reached a consensus), that Imam Hassan Askari has left behind an issue who was the Imam. He said that:  “Anyone who believed the Imamate of eleven Imams from the forefathers of the Qa’im, it is incumbent on him to accept the Imamate of the twelfth, on the basis of the texts from his fore-fathers which contain his name and lineage and the consensus of the entire Shiites on the belief in his Imamate. He is the Qa’im who will appear after a very long Occultation. He will fill the earth with justice and equity. (Ikmal al-Din, p. 44 and 93)

      This is what comes to the mind first these days, when many people argue that the issue of the existence of Imam Mahdi Muhammad bin Hassan Askari, is one of the issues of  consensus of opinion in the ranks of the Twelver-Imam Shiites to say the least.